SAP ASCS High Availability on AWS: Using EFS and Pacemaker
An SAP system on AWS has an SAP Central Services (ASCS) instance running on an EC2 instance. The solution must ensure high availability for the ASCS in case of an EC2 failure. The ASCS uses a shared file system for the /sapmnt and /usr/sap/trans directories. Which architecture meets the high availability requirement with the least administrative overhead?
Quick Answer
The requirement here is high availability for ASCS with the least administrative overhead, and that phrase is the clue pointing toward a managed service rather than a self-built one. Amazon EFS is a fully managed NFS file system that can be mounted concurrently by multiple EC2 instances across different Availability Zones, which is exactly what /sapmnt and /usr/sap/trans need since both must be accessible from wherever the ASCS instance is currently running after a failover. Because EFS handles replication, durability, and availability internally as a managed service, you avoid having to build and maintain your own NFS server, and its own HA story, just to serve these shared directories. Pairing EFS with a Pacemaker cluster spanning two Availability Zones adds the piece EFS doesn't provide on its own: automated detection of an ASCS failure and orchestrated failover of the ASCS resource to the standby node, including the necessary IP and service handling. Together, the two pieces divide the problem cleanly - EFS solves shared storage availability, Pacemaker solves compute-level failover - without requiring the team to operate a bespoke NFS cluster or manage manual snapshot-based replication. When a question emphasizes least administrative overhead alongside a shared file system requirement for SAP central services, that phrasing usually steers you toward a managed storage service like EFS combined with a standard clustering tool, rather than a self-managed alternative.
⚠ Common exam trap
The trap here is that candidates may overlook the need for a fully managed, POSIX-compliant shared file system and instead choose a self-managed NFS server or a non-POSIX solution like S3, not realizing that SAP ASCS requires concurrent access with file locking and low latency.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use Amazon EFS for /sapmnt and /usr/sap/trans, and configure a Pacemaker cluster across two Availability Zones
Amazon EFS provides a fully managed, highly available, and durable NFS file system that can be mounted concurrently across multiple EC2 instances in different Availability Zones. By using EFS for /sapmnt and /usr/sap/trans, and configuring a Pacemaker cluster across two AZs, you achieve automatic failover for the ASCS instance without the administrative overhead of managing a separate NFS server or replicating snapshots.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Deploy a second ASCS instance in another AZ and use an EC2 instance running NFS server with an EBS volume
Why it's wrong here
This adds complexity and a single point of failure on the NFS server.
- ✗
Use an Amazon EBS volume attached to the ASCS instance and replicate it to another Availability Zone using EBS Snapshots
Why it's wrong here
EBS volumes cannot be attached to multiple instances; snapshots are not real-time.
- ✗
Use Amazon S3 and mount it using s3fs-fuse for the shared file system
Why it's wrong here
S3 is not POSIX-compliant and s3fs-fuse is not recommended for SAP.
- ✓
Use Amazon EFS for /sapmnt and /usr/sap/trans, and configure a Pacemaker cluster across two Availability Zones
Why this is correct
EFS is a managed NFS file system that is highly available and integrates with Pacemaker for automatic failover.
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Same concept, more angles
1 more way this is tested on PAS-C01
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company is migrating its SAP ERP system to AWS. The system includes an SAP Central Services (ASCS) instance and an SAP application server. Which TWO of the following are required for high availability? (Choose TWO.)
hard- A.Use an EBS Multi-Attach volume for shared /sapmnt
- ✓ B.Enqueue replication server (ERS) must be set up for the ASCS cluster
- C.Configure an Elastic Load Balancer for ASCS
- ✓ D.Set up a cluster for ASCS using AWS cluster management tools
- E.Deploy at least two application servers in different Availability Zones
Why B: The Enqueue Replication Server (ERS) is a mandatory component for an SAP ASCS high-availability cluster. In a clustered ASCS setup, the ERS replicates the lock table from the active ASCS node to the standby node, ensuring that in the event of a failover, the new active ASCS instance can recover the locks without data inconsistency. Without ERS, the ASCS cluster cannot provide true high availability for the enqueue service.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PAS-C01 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PAS-C01 exam.